1. Field of the Invention
The present invention generally relates to a character recognition apparatus and, more particularly, to a hand-written character recognition apparatus.
2. Description of the Prior Art
Hand-written character recognition apparatus of the on-line type generally execute the following two steps. That is,
first step: to extract various characteristics (stroke data) from strokes of a hand-written character manually written on a tablet; and PA1 second step: to compare the extracted stroke data with the characteristics (evaluation codes) of characters stored in a character recognition dictionary and output a character code of a character which is sufficiently identical with the evaluation code stored in the dictionary.
When the processing in the second step is carried out, a Japanese Kanji character is decomposed into partial structures such as a left-hand side radical, a right-hand side radical or the like and the character recognition dictionary is formed on the basis of such partial structures. This type of dictionary will be referred to hereinafter as "partial structure dictionary". If the character recognition dictionary is formed such that the parts whose comparison and evaluation are common comprise the partial structure dictionary, the storage capacity of the character recognition dictionary can be reduced.
The writing order of Kanji characters, i.e. the order in which the strokes are written, is not always kept constant and writers often use different writing orders.
Accordingly, a hand-written character recognition apparatus must cope with writers' various different writing orders so that several writing orders must be prepared in the partial structure dictionary to thereby alleviate any restriction on the differences of the writing orders.
However, it is frequently observed that, even when a plurality of writing orders are intended to be prepared in the partial structure dictionary, there is the case that a directional relation of two partial structures of the character can not be evaluated. As a result, the recognition speed of the input character is lowered and interference between characters is increased, thereby reducing the recognition ratio of the character.